The primary purpose of this research proposal is to further understanding of the role of platelet lipids in the pathogenesis of thrombosis. It is proposed to define the pathways of lipid metabolism within the platelet and to examine the specific alterations that occur in association with rendering platelet lipids available to participate in blood clotting, and thereby participate in the formation of thrombosis in areas of rapid blood flow. Using in vitro incubations with radioactive precursors, the pathways of lipid synthesis in intact human platelets is currently under investigation. We have characterized the pathways of synthesis of lipids from acetate and palmitic acid. We are now examining the alterations induced in platelet lipid metabolism by thrombin and other platelet aggregating agents.